Alimentary microbes of winter-form Drosophila suzukii.

Drosophila suzukii (Matsumura) (Diptera: Drosophilidae) is a damaging pest of fruit. Reproductively diapausing adults overwinter in woodlands and remain active on warmer winter days. It is unknown if this adult phase of the lifecycle feeds during the winter period, and what the food source may be. This study characterized the flora in the digestive tract of D. suzukii using a metagenomics approach. Live D. suzukii were trapped in four woodlands in the south of England and their guts dissected for DNA extraction and amplicon-based metagenomics sequencing (internal transcribed spacer and 16S rRNA). Analysis at genus and family taxonomic levels showed high levels of diversity with no differences in digestive tract bacterial or fungal biota between woodland sites of winter-form D. suzukii. Female D. suzukii at one site appeared to have higher bacterial diversity in the alimentary canal than males, but there was a site, sex interaction. Many of the biota were associated with cold, wet climatic conditions and decomposition. This study provides the first evidence that winter-form D. suzukii may be opportunistic feeders during the winter period and are probably exploiting food sources associated with moisture on decomposing vegetation during this time. A core gut microbiome has been identified for winter-form D. suzukii.

Brain and Cardiorespiratory Responses to Exercise in Hot and Thermoneutral Conditions.

The aim of this study was to test whether or not concurrent evaluations of brain (electroencephalography [EEG]) and cardiorespiratory responses to exercise are influenced by environmental conditions. 10 adult male participants performed a standardized incremental exercise test to exhaustion on a cycle ergometer in an environment controlled laboratory on 2 separate occasions, in a randomized order; one in a hot condition (34.5°C) and one in a thermoneutral condition (20°C). EEG, heart rate and expired air were collected throughout. EEG data were decontaminated for artefacts, log-transformed and expressed as aggregated alpha and beta power responses across electrodes reflecting the frontal cortex of the brain. Performance outcomes showed there was no difference in V˙O2 peak across hot (42.5 ml/kg/min) and neutral (42.8 ml/kg/min) conditions, although ventilatory threshold (VT) occurred at a lower threshold (68%) in hot compared to neutral condition (74%) (p<0.05). EEG alpha and beta wave responses both demonstrated significant increases from baseline to VT (p<0.01). EEG beta-band activity was significantly elevated in the heat compared to the neutral condition. In conclusion, elevated EEG beta-band activity in response to incremental exercise in the heat suggests that beta-band activation and cortical awareness increases as exercise becomes increasingly intense.

The reliability of lower extremity and thoracic kinematics at various running speeds.

Whilst various studies have examined lower extremity joint kinematics during running, there is limited investigation on joint kinematics at steady-state running and at intensities close to exhaustion. Subsequently, the purpose of this study was to determine whether the reliability of kinematics in the lower extremity and thorax is affected by varying the running speeds during a running economy test. 14 trained and moderately trained runners undertook 2 running economy tests with each test incorporating 3 intensity stages: 70-, 90- and 110% of the second ventilatory threshold, respectively. The participants ran for 10 min during each of the first 2 stages and to exhaustion during the last stage. Kinematics of the ankle, knee, hip, pelvis and thorax were recorded using a 3-dimensional motion analysis system. Intra-class correlation coefficient (ICC), limits of agreement (LOA) and coefficient of variation (CV) were used to calculate reliability. The ICC, LOA and CV of the lower extremity and thoracic kinematic variables ranged from 0.33-0.97, 1.03-1.39 and 2.0-18.6, respectively. Whilst the reliability did vary between the kinematic variables, the majority of results showed minimal within-subject variation and moderate to high reliability. In conclusion, examining thoracic and lower extremity kinematics is useful in determining whether running kinematics is altered with varying running intensities.

What is the dose-response relationship between exercise training and blood pressure?

Most studies of exercise and blood pressure have used a standard exercise programme with a single level of physical activity. To determine the nature of the dose-response relationship however it is necessary to examine several levels of activity, preferably in the same subjects. We have recently performed several randomised crossover studies comparing different levels of regular exercise. The intensity and duration of exercise bouts were constant throughout the studies, but their frequency was varied. Standard bouts consisted of 30 min of bicycling at 60%-70% of maximum work capacity. The exercise was performed either three-weekly or 7-weekly in randomised order and each level was maintained for one month. In sedentary normal subjects three bouts of exercise/week for a total of 90 min lowered blood pressure by 10/7 mmHg. With seven bouts, i.e. a total of 210 min exercise/week, blood pressure was only slightly lower than 3-week exercise and was 12/7 mmHg below sedentary values. Responses to measures of physical fitness including maximum oxygen consumption and work capacity were linearly related to the amount of exercise performed each week. Similar results were obtained in hypertensives. Another randomised study was performed amongst expeditioners to Antarctica where environmental conditions determined that they were sedentary in winter and active in summer. The addition of either 3-week or 7-week exercise in winter significantly lowered blood pressure. In summer when the background level of activity was higher, blood pressure with no added exercise was similar to exercising levels in winter. There was no further fall in blood pressure with either 3-week or 7-week additional exercise.(ABSTRACT TRUNCATED AT 250 WORDS)

Exercise, cardiovascular disease and blood pressure.

The "chronic" effect of exercise on blood pressure has been controversial and the debate has been confused by a large number of studies with inadequate methodology. Recent consistent findings in epidemiological, experimental and longitudinal intervention studies have suggested that a true antihypertensive effect which is independent of confounding effects of sodium intake, weight, etc. is more likely than not. Unlike some other measures of lowering blood pressure such as sodium restriction, alcohol moderation and some drugs, regular exercise is associated with beneficial effects on several risk factors and probably has an independent effect on cardiovascular mortality. The magnitude of the effect in previously sedentary subjects is greater than that of dietary measures which lower blood pressure except for weight reduction in the obese. Long-term effects on blood pressure are supported by evidence of a favourable influence on left ventricular hypertrophy. The mechanisms involved in the antihypertensive effect of exercise are unclear, but sympathetic withdrawal is one factor involved. Present evidence appears sufficient to include regular exercise amongst the useful therapies for hypertension.